1. Field of the Invention
In accordance with the classification of art as established by the United States Patent Office this invention is found in the general Class entitled, "Agitating" (Class 259) and the subclass therein entitled, "miscellaneous" (subclass 1) which has been further indentified in this subclass as "1R" and "DIG. 43". The method of making a vibration apparatus as in the embodiment shown is found in the general Class entitled, "Metal Working" (Class 29) and the subclass therein of "impellers" (subclass 156.8).
2. Description of the Prior Art
Air turbines are not new and making the rotor with an eccentric weight is also well known as seen in U.S. Pat. No. 3,074,151 to KROECKEL as issued on Jan. 22, 1963. Another patent using the same general concept includes U.S. Pat. No. 2,875,988 to WYSONG as issued on Mar. 3, 1959. Other air driven vibrators also generally used include ball-type vibrators as seen in U.S. Pat. Nos. to PETERSON, No. 2,793,009 as issued on May 21, 1957 and 2,917,290 as issued on Dec. 15, 1959. In the above apparatus as well as others known to the applicant the noise levels exceed the tolerance levels for continuous duty operation (ie. 85 db) as established by the Federal Occupational Safety and Health Act of 1970.
The turbine-type pneumatic vibrator of this invention, as reduced to practice and extensively tested and used in commercial installations, operates substantially continuously at noise levels well below the established 85 db and with the associated muffler operates at levels of 60 to 70 db. This, of course, falls well within the safety limits of the federal standard. In sharp contrast to this "quiet" vibrator is the ball-and-race vibrator now and for the past several years in extensive use. This ball-and-race vibrator is shown and described in U.S. Pat. Nos. 2,793,009 as issued on May 21, 1957 and 2,917,290 as issued on Dec. 15, 1959 both to PETERSON. The noise level usually found in the installations of these ball-and-race vibrators is often in excess of 100 db. This noise level for periods of 8 or more hours, of course, is unacceptable.
In the present invention the size of the rotor, the number and depth of teeth used therewith and the normal operating range of air pressure used to drive the vibrator are closely related factors. The air turbine vibrator of this invention uses a close limit control of these factors to successfully exceed the safe requirements for a "quiet" operation of the vibration apparatus.